A hint for all #podmins that might want to upgrade their #Ubuntu base to 22.04. ("Jellyfish"?)
In 22.04 the openssl lib defaults to v3.0, which is not compatible with ruby 2.6 or 3.

Try downloading and installing openssl 1.1 in your user space and install ruby with this:

rvm install 2.6 --with-openssl-dir=$HOME/.openssl/openssl-1.1.1g

A full and detailed description to install ruby on 22.04 I found here: https://deanpcmad.com/2022/installing-older-ruby-versions-on-ubuntu-22-04/